Most aircraft windows have shades to control the amount of light entering the interior of the aircraft. The simplest aircraft window is typically comprised of retractable shade material with a rail along the bottom. The rail typically has a tab that can be gripped by the passenger for sliding vertically between a closed (usually down) position, in which the window is covered, and an open (usually up) position, allowing light into the cabin.
However, many aircraft, including typically those in the executive jet aircraft class, have rather expensively appointed interiors, including custom designed windows. Sometimes these windows are electric, sometimes manual, or sometimes electric with manual overdrives. These custom interiors also may feature modular windows with shades located between an inner lens and an outer lens and activated by a mechanical or electrical mechanism operated by the passenger. These modular windows, often built by after-market supply firms and fitted at modification centers ("mod centers"), have shades made of a variety of materials; but typically, the materials are collapsible between an extended (down or closed) position and a retracted (up or open) position. An example of such a modular window unit with a retractable shade may be found in U.S. Pat. No. 4,679,610 (Spraggins, 1987). The '610 patent features a modular, self-contained window unit having two panes of transparent, impact-resistant glass secured by a frame and having a shade made of a collapsible sheet movable between an open and closed position.
Shade materials are typically pleated and collapsible with sufficient rigidity to maintain their shape, form, and uniformity. Manufacturers of present window shade material include Hunter-Douglas. However, shade material suppliers are limited in the styles and color section which can be provided.
Advantages exist in being able to use any upholstery material or fabric. The use of any upholstery material or other fabric increases the design opportunity available to the interior designer for coordinating the colors and textures of the interior of the aircraft to the window shade material. Thus, greater flexibility is provided in an aircraft window shade which can use any flexible fabric, rather than the limited selection of presently available shade materials.
Some of the present aircraft windows utilize a "Roman shade", that is, one having horizontal pleats. These, however, utilize a bar or rod, or a series of bars or rods, extending horizontally across the windows. From these bars or rods is a draped fabric, typically backed with thin foam (such as Insulite). The bars or rods are raised and lowered, deploying fabric as they are lowered and gathering it up as they are raised. Typically, the fabric is a single sheet with multiple pleats and multiple bars or rods. It does not tend to hold its shape well, tends to be heavy, and bulky, especially when the shade is in a raised or up position. Further, it has a limited ability to block out heat, light, and sound, even when in a down or closed position.
Aesthetics are a very important consideration in the design of aircraft interiors, including windows, especially for private or corporate jets. For example, in the aforementioned shade, it is more attractive to conceal as much of the mechanical mechanism which raises and lowers the shades as possible. Some mechanical window shades utilize chains, cables, or the like to raise and lower the shade, which means are often visible to the passenger, especially if the passenger looks through the window at an oblique angle.
Moreover, when the shade to be raised and/or is a "Roman shade" or a shade made of discreet horizontally segmented panels, it is desirable that, when such shade is raised or lowered, the separation between the pleats (or panels) remains proportional. That is, when the shade is in a down position (lowered or closed), the pleats (or panels) are a certain distance apart. As the shade is raised, it is aesthetically desirable for the distance between the adjacent pleats (or panels) to decrease proportionately rather than, say, the lowest pleat collapsed to the one just above it and have a successive piling up of the pleats (or panels) as the shade is raised. It is also important in a shade that the pleats (or panels) be kept parallel to one another and perpendicular to the edges of the window. In other words, as the shade is raised and lowered, it is important that the pleats (or panels) be kept parallel and the proportional separation of adjacent pleats (or panels) decrease and increase proportionately as the shade is raised and lowered. Last, it is important to have the ability to use non-opaque panels as pleats (the panels being covered with fabric). Non-opaque panels especially assist in visible and ultraviolet light for further passenger comfort. Such panels also help keep the fabric neater and straighter during window shade operation.